Fuse medium



PATEN FHCE.

FREDERICK A. FELDKAMP, OF NEWARK, NEW JERSEY.

FUSE MEDIUM.

No Drawing.

T 0 all whom it may concern:

Be it known that I, FREDERICK A. FELD- KAMP, a citizen of the UnitedStates, residing at Newark, in the county of Essex and State of NewJerse have invented certain new and useful mprovements in Fuse Mediums;and I do hereby declare the following to be a full, clear, and exactdescription of the invention, such as will enable others skilled in theart to which it appertains to make and use the same, reference being hadto the accompanying drawings and to characters of reference markedthereon, which form a part of this specification.

This invention relates to improvements in electrical metallic fusemediums; and the invention has reference, more particularly, to a novelcomposite metallic fuse material, consisting of a plurality of metallicelements, so related and combined as to provide a novel physicalinterrelation thereof forming an amorphous but united mass, adapted tobe readily disintegrated under the influence of comparatively hightemperature.

It is generally recognized that an ideal electrical fuse is one whichwould possess both high specific conductivity and low melting point. Inthe range of metallic materials suitable for use in an electrical fuse,it happens that metals having a hi h specific conductivity also possessa hig melting point; while metals having a low melting point ofiercomparatively high resistance, i. e., possess low specific conductivity.If it is sought to provide the desired ideal characteristics of highspecific conductivity and low melting point by forming an alloy of metalpossessing one desired characteristic with a metal possessing the otherde sired characteristic, the results obtained are not satisfactory, forthe normal high specific conductivity of the one metal is reduced andthe low melting point; of the other metal is increased in the resultantfusion or alloy of the two.

I have discovered that two metals, respectively possessing the desiredcharacteristics of high specific conductivity and low melting point, maybe combined to form a united or integral mass in such a manner that amaximum retention of the aforesaid desired characteristics is attained,and that consequently a highly efficient and compara tively ideal fusemedium is thereby pro vided. It is the object of this invention,therefore, to provide a composite metallic Application filed September26, 1924.

Serial No. 740,104.

fuse material possessing comparatively high specific conductivit and lowmelting point in the form 'of a united or integral mass possessingcohesion and ductility, whereby the same may be cold rolled, drawn ormachine worked to produce therefrom any desired shape or form ofelectrical fuse, but which, by reason of the novel physical relation ofthe metallic elements in physical combination, provides a mass whichquickly disintegrates under the influence of comparatively hightemperature.

In the subsequent detail description of my invention I have taken, forthe purposes of illustrai ion, copper as the metallic elementrepresentative of the high conductivity class, and tin as the metallicelement repre sentative of the low melting point class. In so doing,however, I do not intend to be understood as limiting my invention tothe use of such particular metallic elements, since, 111 its broadaspects, my invention is intended to include any metals, or even alloys,in the respective classes, which are capable of being physically unitedor combined in the manner hereinafter set forth.

In producing my novel composite metallic fuse material, I take copperwhich has been reduced to a finely divided state, that is in the form ofa powder or mass of small particles or granules. A suitable quantity ofsuch finely divided copper is compressed into a block-like looselyadhering comparatively porous mass. The loosely adhering mass may thenbe immersed in suitable soldering flux, and thereupon dipped into moltentin or solder-like alloy. The molten tin or solder-like alloy willpenetrate the interstices of the loosely adhering 'mass of copperparticles, and will bond such copper particles together in a physicallyunited integral mass. The surplus molten tin or solder-like alloy isdrained away while the mass is hot, whereupon the mass may be submittedto pressure, at a suitable temperature, to further extrude surplus tinor solder-like alloy, while at the same time consolidating the resultantmass to desired density. The resultant mass is allowed to cool, thusforming What may be termed an ingot of my novel fuse material which maybe worked cold by rolling, drawing, stamping or by suitable machinemethods to produce any shape of finished electric fuse desired. It willbe understood, that any other method found feasable to physically unitethe metallic elements of my material may be employed.

In the novel material, obtained by the above described or any othersuitable method, there is and should be a marked preponderance of thecopper element, so that the relative quantity of tin is as small aspossible; in fact, there should be, sub stantially, only that amount oftin present which is sufficient to bind the copper particles together.Fuses made from my novel composite metallic material will have a veryhigh conductivity, as 80 per cent or more, as compared with copper fusesclassified as 100 per cent, depending upon the relative quantity of thematerials used, while at the same time I have retained, in such fuses, alow melting point equivalent to the melting point of tin alone(approximately 230 degrees 0.). These results are due to the fact thatthe metallic elements making up the novel fuse material, to wit, copperand tin, are merely mechanically combined, and are not alloyed orintermingled by fusion, or in any way chemically compounded, and,consequently, each metallic element retains its particular inherent anddesired characteristics substantially unmodified; in other words, thecopper remains pure copper and supplies a high specific conductivitycharacteristic to the fuse, and the tin or soldering alloy remainsunmodified and supplies the desired low melting point characteristic.

It will be evident that the normal melting point of the material may belowered or raised by employing metal or alloys, other than tin, whichpossess the melting point desired.

Besides the advantages of providing a comparatively high specificconductivity combined with a comparatively low melting pointZmy novelcomposite metallic fuse material, by reason of the character of theunion efl'ected between the copper particles by the tin bond, provides amass having what may be termed an amorphous internal or physicalstructure, as distinguished from a fibrous internal or physicalstructure such as would be possessed by copper alone or alloys of copperand low melting point metal. As a consequence of its amorphous internalor physical structure, when, in service, the temperature of the fuse israised by the effects of abnormal overloads or short circuits and thefuse blows, the tendency of the material is to quickly disintegrate;

. that is, the low melting point metal quickly fuses or liquefies, thuseliminating the bond between the particles of copper, so that the latterdrop away from the body of the fuse, thus quickly disintegrating thesame, at the blowing point and quickly forming a circuit breaking gap,instead of forming an are requiring the consuming or vaporizing of thematerial until a gap of critical dimension is reached. This desirabledisintegrating effect of my novel fuse material under comparatively hightemperature, is quickly brought about for the reason that the incorporated particles of copper impart to the -material a high internalconductivity of heat, with the result, that on both sides of thebreaking or blowing point of the fuse, the material is rapidly broughtto the melting temperature of the binding metal, whereby gravity may actupon the freed particles of copper to cause the same to drop bodily awayfrom the mass until a gap of critical dimensions is produced.

It will be understood that owing to the characteristic advantages of mynovel fuse material above pointed out, it is possible to employ fuses ofcomparatively small mass according to the rating desired, andconsequently such fuses will be more rapidly acting and safer than isthe case with ordinary single metal or metallic alloy fuse links ormembers heretofore in use.

lVhile I have described above, as the two metallic elements combined toform my novel fuse material, other metallic combinations may beemployed, viz, silver and tin (or lead and tin solder); aluminum andaluminum solder; or in fact any other combination of metallic elementsmay be employed to produce a product suitable for electric fuses andcoming within my invention, so long as the two physically combinedmetals, one highly conductive and the other low melting do not unite asor form an alloy.

Ilaving thus described my invention, I claim 2- 1. A composite metallicfuse material consisting of a mass of metallic particles possessingrelatively high 5 ecific conductivity bonded together by a lbw meltingpoint metal.

2. A composite metallicfuse material comprisin a preponderance of acomminuted metallic element possessing relatively high specificconductivity formed into a mass with its particles adhesively connectedby a relatively small proportion of a low melting point metal.

3. A fuse material comprising a mass of comminuted metal of-comparatively high specific conductivity, the particles of which arebonded together by a solder-like metal.

4. A fuse material comprising a mass of comminuted metal ofcomparatively high 6. A fuse material comprising granular metallicparticles possessing relatively high specific conductivity compactedtogether and v interspersed with a metal of relatively low melting pointwhich serves to bond the granular particles together.

7. A fuse material comprising a preponderanc'e of metal of relativelyhigh specific conductivity in finely divided state combined with acomparatively small proportion of a low melting point solder-like metal.8. A fuse material comprising a preponderance of metal of relativelyhigh specific conductivity in finely divided state combined with acomparatively small proportion of a low melting point solder-like metal,the latter metal joining the particles of the former metal into acompact mass having an amorphous internal structure.

9. A fuse material comprising a relatively porous mass of coppercontaining tin in the interstices thereof.

In testimony, that I claim the invention set forth above I have hereuntoset my hand this 24 day of September, 1924.

FREDERICK A. FELDKAMP.

